A sponge when brought to the surface by the diver is a fleshy-looking
substance covered with a firm skin whose openings appear and disappear
at intervals. When the diver cuts it the interior looks like raw meat
with numerous canals and cavities. The first thing they do is to remove
the flesh, and this must be done at once, since otherwise putrefaction
would set in, which would destroy the elasticity. This leaves merely
the skeleton of the animal which has to be further cleansed before it
is ready for the market.
The skeleton is nearly related in structure to silk, and this helped
to settle the ancient dispute as to whether sponges were animal or
vegetable. Their stationary life gave reason to the belief in their
vegetable nature, while they multiply, like plants, by overgrowth and
budding. They puzzled scientists for centuries, and one authority
regarded them as worms' nests. In reality the sponge is a colony of
little animals called polyps which occupy a sort of apartment house
together, rearing families just as other animals do.
The surface of a sponge is covered with little holes, as you have
observed, that are larger at the top than at the bottom, while the
whole mass contains a system of channels. When the animal is alive
water is kept flowing constantly through these channels by means of
minute, hair-like appendages, which the little polyps agitate. The
water thus drawn in brings with it the food.
The finest sponges come from Tripoli, and along the shores of the
Mediterranean, the possessions of Turkey being the best field, the
Spanish, French, and Italian coasts being, strange to say, devoid of
them. The coarser kinds of sponges are found in the West Indies and
off the Florida coast, none of the finest grade existing in American
waters. The average value of Florida sponges is 80 cents a pound,
while those from the Turkey coast are often worth as much as $50 a
pound. There are many sponge beds along the coast of Florida, at
well-protected places fenced in with natural fortifications and dams.
They are carefully watched until reaching maturity, and are finer than
those living wild in the sea.
After three years the sponges are ready for harvest. The choicest then,
the full-grown ones, are pulled up, the others being left to reproduce
until of larger size. Every year the value of a sponge farm increases,
and enormous crops are yielded. It is easy to gather sponges here, for
the water is clear and they are easily raised with a pole or tongs.
It is not so in Tripoli, however. There the work has to be done by
divers, and as the fisheries have been so well worked, it is necessary
for the divers to go deeper and deeper for them every year. Only the
most desperate men are willing to undertake the task, notwithstanding
they are paid ten times the usual wage paid to men in that country.
Out of 600 divers employed, 150 to 200 die each season, either from
asphyxiation, paralysis, or cuts from their knives. The diver in
Tripoli seldom has diving-bells or suits such as are used in Europe and
America. He goes down into the ocean, sometimes to the depth of 100
fathoms, taking with him a flat piece of stone of a triangular shape,
with a hole drilled through one of its corners. A cord from the boat is
attached to this stone and he uses it to guide him. Upon reaching the
growing sponges he tears them off the rocks or cuts them with a sharp
knife, places them under his arms, and then pulls at the rope, which
gives the signal to the men in the boat to haul him up. The work is
said to be done not so well by means of a diving-bell, the utmost care
being necessary that the delicate organisms should not be torn. Sponges
obtained by dragging are torn and sell for low prices. Those secured at
such risk are the best and are used by surgeons in delicate operations.
They do not grow as rapidly in the Mediterranean as in our water, an
ordinary bath sponge, measuring about a foot in diameter, being ten
years old.--_E. K. M._